I would only say the following. " It's close to your example 4, but I added the necessary period. There is no need for a comma.
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vcoltsI checked several sites on quotations and practically all of them show that you don't use a capital when you introduce it as a surbordinate (that clause). The period was a type issue.But what if they agreed on that by both writing exactly 'Crimes happen more in the slums.'